I. Field of the Invention
This invention relates generally to the design of cleaning systems for industrial heat-exchanger coil arrays and more particularly to an assembly and mechanism for cleaning layers of finned coils to remove particles of dust and debris that have become entrapped within the joints and crevices of such coil arrays.
II. Discussion of the Prior Art
Prior attempts to thoroughly cleanse all regions of the fins of cooling assemblies using forced spray jets of cleaning fluids have not been entirely successful. It is difficult to access fins embedded within the array to dislodge particles of dirt and debris. Of the two general types of heat exchangers, devices have been designed to clean rotary heat exchangers, but the problem of cleaning stationary banks of heat exchanger coils has not been adequately solved. The present invention solves this problem for stationary heat exchangers by subdividing a lengthy bank into sections and directing jets of cleaning fluid to impinge upon individual fins to dislodge dirt and debris. Due to their rotating nature, rotary heat exchangers address an entirely different application than that of stationary heat exchangers. Also due to their rotating nature, it is necessary that the sprayers directed at rotary systems be positioned along the periphery and utilize directed jets of forced spray. Our experiments have shown that such an approach with stationary heat exchangers fails to cleanse all regions.
In U.S. Pat. No. 4,141,754, issued to Frauenfeld, there is disclosed both apparatus and method for cleaning the heat exchanging surfaces of the heat transfer plates of a rotary regenerative heat exchanger. Generally, ambient heat exchanging gas or air is mixed with a medium pressure jet of cleaning agent and the mixture is directed at high velocity into the interspaces between the heat transfer fins or plates of the rotating heat exchange unit. The high velocity injection of cleanser is accomplished using injection-type nozzles to produce directional jets of steam or gas cleaning agents aimed towards injection tubes. Ambient heat exchanging gas or air is sucked into these tubes along with the cleaning agents, and turbulence therein mixes them. The mixture is then blown upon the interspaces between heat transfer plates using supersonic nozzles.
A method of applying a generally flat, fan-shaped spray to the side and top surfaces of cooling fins is disclosed in U.S. Pat. No. 4,589,898 to Beaver. The invention is directed primarily to the proportional percentages of solvents used and is expressly designed for removing boron oxide contaminants from fin surfaces in a glass fiber forming bushing assembly.
A plurality of coil-cleaning nozzles is disclosed in U.S. Pat. No. 4,332,292 to Garberick. These nozzles are mounted at the ends of highly flexible hoses which, in turn, are connected to relatively rigid supply lines fed from a medium supply source. These flexible tubes are positioned in front of the coil they are intended to clean and can be operated either simultaneously or individually to spray pressurized cleaning medium toward the coil. The nozzle itself is an elongated, relatively narrow slot mounted at the distal end of a highly flexible tube. The tubing selected is so sensitive to pressure that flow of the pressurized cleaning medium causes a "whipping action" that disperses the cleanser fluid.
The stationary finned cooling units currently in use in the food industry are generally much larger and bulkier than the rotary units cleansed by the Frauenfeld '754 device described briefly above. In addition to their non-analogous nature of use, rotary heat exchanger units are inherently more cleanable by a stationary spray head or spray tube because as the unit rotates, most regions of the surface pass into the trajectory of the impinging sprays. In our attempts to devise a system which would clean stationary banks of heat exchanger coils, we have instead found it necessary to provide a mechanism which will move across the surface of such banks. Although it is possible to use the Beaver '898 and Garberick '292 sprayers to cleanse stationary, squared banks of layered heat exchanger fins, they are incapable of accessing all regions of the bank to a degree adequate to satisfy, for example, the stringent cleanliness requirements of the food processing industry.
It is accordingly a principal object of the present invention to provide a new and improved method and apparatus for automatic cleansing of layers of stationary, finned industrial coils without the necessity for removal of the coils from their mountings.
Another object of the present invention is to provide a method and apparatus for thoroughly cleansing difficult to reach regions between layers of stationary, finned heat exchanger coils.
It is yet another object of the present invention to provide a method and apparatus for enhancing sanitation in, for example, the food processing industry by providing a means for periodically, automatically and more thoroughly cleaning such finned heat exchanger coil arrays.
A further object of the present invention is to provide a rotating spray arm arrangement that can be interspersed between rows of industrial heat exchanger coils for providing a cleansing spray thereto, and which is capable of cleaning all regions of a bank of coils of substantial depth dimension.
A still further object of the present invention is to provide a method and apparatus for a laterally traversing spray assembly that is interspersed between plural stacked arrays of heat exchanger coils for providing a cleansing spray capable of reaching all regions of the heat exchanger.